Waist-to-height ratio is the proximal correlate of workload-indexed exercise systolic blood pressure: a Czech preventive-cardiology cohort study

BACKGROUND: Exercise systolic blood-pressure (SBP) response predicts incident hypertension and cardiovascular events independent of resting BP, but guidelines disagree on the threshold for an exaggerated response and absolute peak-SBP cut-offs misclassify fit individuals. We examined determinants of workload-indexed exercise SBP and tested whether central adiposity statistically accounts for the cardiometabolic signal. METHODS: Cross-sectional analysis of 324 working-age adults from a Czech preventive-cardiology cohort with a valid bicycle cardiopulmonary exercise test. The pre-specified primary endpoint was peak SBP indexed by relative workload (peak SBP ÷ W·kg⁻¹). Confirmatory multivariable linear regression was fitted; statistical mediation of HOMA-IR and the triglyceride/HDL ratio through waist-to-height ratio (WHtR) was formally tested; binary outcomes were analysed under parallel ESC, AHA and workload-adjusted definitions. RESULTS: WHtR was the dominant predictor (β = +8.96 mmHg per W·kg⁻¹ per 1-SD, p < 0.001; R² = 0.61) and remained significant across all eleven workload-indexing methods (including the SBP/MET slope and after VO₂peak adjustment), and predicted peak SBP itself (p < 0.001). WHtR accounted for 80-90% of the effect of both insulin-resistance surrogates (Sobel p < 0.001). The association was age-modified (p = 0.014) and independent of sex (sex × WHtR p = 0.31). ESC and AHA definitions reclassified 47/324 patients (14.5%) discordantly (κ = 0.67). A workload-adjusted definition (SBP/MET slope > 10 mmHg·MET⁻¹) classified 24.4% yet reclassified one in five versus ESC and showed no age dependence. CONCLUSIONS: WHtR is the proximal anthropometric correlate of workload-indexed exercise SBP, statistically accounting for 80-90% of the insulin-resistance signal; the association is robust to the choice of workload-indexing method and largely independent of resting BP. ESC and AHA definitions classify approximately one in seven patients discordantly, motivating harmonisation.